1. Field of the Invention
The present invention relates to an optical information recording medium exhibiting excellent print water resistance and having an ink receiving layer, which can be printed directly, on a surface (label surface) opposite to a recording and playback surface of the optical information recording medium.
2. Description of the Related Technology
A Medium having an ink receiving layer, which can be printed directly with an ink-jet printer or the like, on a label surface of an optical information recording medium (a so-called printable product) has become widely used.
Here, the ink receiving layer of the printable product is allowed to be printed with images and characters by absorbing and fixing a water based ink of an ink-jet printer. Therefore, in general, the layer is composed of a raw material primarily containing a hydrophilic resin. On the other hand, since the ink receiving layer has a hydrophilic function, there is a problem in that the water resistance is poor.
In contrast to the case where printing is performed on common paper or the like, since the printable product has two functions including a printing function and a function as an optical information recording medium, usually, the printable product is handled in such a way as to avoid touching directly the recording and playback surface side with a finger or the like in order that the function as an optical information recording medium does not deteriorate. That is, opportunities to handle while touching a surface (a label surface) opposite to the recording and playback surface are increased, and the improvement of the durability of a printed surface has become an even more important factor as compared with that in the case where printing is performed on paper or the like.
The invention related to “an optical recording medium including a printing receiving layer as an outermost layer of the medium, wherein the printing receiving layer is formed from an ultraviolet curing resin composition containing fine particles having an average particle diameter of 200 nm or less and a cationic resin” has been known as the optical information recording medium having an ink receiving layer exhibiting excellent print water resistance (refer to Japanese Unexamined Patent Application Publication No. 2000-57635).
In this invention, with respect to the water resistance of the image, solid printing is performed with different two colors, A and B, selected from four colors of cyan, magenta, yellow, and black (the combinations of the color A and the color B are 12 types), after 1 hour, about 1 cc of water is dropped on the image portion, standing is performed at room temperature for 1 minute, wiping is performed with a clean room wiper, a state of elution of the ink of the image portion is evaluated visually, and it is ascertained that the ink is not eluted, nor occurs change in the color (paragraph [0058]). However, since the printing receiving layer (ink receiving layer) primarily contains the ultraviolet curing resin composition, it may not be said that the water resistance of the ink receiving layer is satisfactory.
On the other hand, as a trend in the printable product market, printable products having a gloss have become appeared. The ink receiving layer is allowed to have a function of gloss so as to become upscale-looking. This product has a high level of gloss superior to that of known printable products.
In association with this, the invention related to “an optical recording medium including an ink absorption resin layer as an outermost layer having a 60-degree specular glossiness of the surface of 30 or more, and 150 or less” has been known (refer to Japanese Unexamined Patent Application Publication No. 2002-237103).
However, the water resistance of these products are the same level as the level of the known product, and the color tends to fade.
There is also a product of the type, in which highly water-resistant paper (so-called water-resistant photo paper) is attached to a label surface. The durable image quality is realized by attaching the paper (image) printed with a printer or the like to the label surface.
As described above, there is an effort afoot to improve an upscale image and functions, e.g., durability, of the printable products.
When printing is performed on the durable photo paper, high quality printing exhibiting durability after the printing can be realized. However, there is a problem in that functions (optical recording and playback) as an optical information recording medium tend to be impaired significantly. Specifically, the deflection in rotation tends to occur due to misalignment in attachment of a label, accuracy in the weight distribution of paper itself, or the like. Furthermore, warpage tends to occur due to deformation (expansion, shrinkage, or the like) of the label itself. These tend to cause errors during recording or playback. Moreover, there is a risk that the attached label begins peeling or is peeled off. In this case, the label may get snagged on a drive device so as to cause breakage of disk or drive.
Consequently, with respect to the printable product, in which an ink receiving layer is disposed directly on a label surface of an optical information recording medium without attaching water-resistant photo paper, a technology to ensure high durability is required in order that the color of the image or character after printing is not easily faded even when being rubbed.